Water immersion thermostat and method for using thereof

ABSTRACT

An improvement in a water immersion thermostat having a longitudinal sleeve for being deeply substantially-immersed in water of a storage water heater, the improvement including a thermal fuse disposed within the longitudinal sleeve, for single-use cutting of electrical connection upon temperature of the water within the storage water heater exceeding a pre-adjusted temperature threshold, and serial wiring of the thermal fuse between the power supply and the heating element of the storage water heater, thereby permanently cutting the power supply from the heating element upon presence of extreme temperature deep in the storage water heater.

FIELD OF THE INVENTION

The present invention relates to the field of storage water heaters. More particularly, the invention relates to a water immersion thermostat.

BACKGROUND OF THE INVENTION

FIG. 1 depicts a prior art thermostat for a storage water heater.

In household and commercial usage, common water heaters are of the tank type, called storage water heaters. Typically they include a cylindrical vessel in which water may be stored is kept continuously hot and ready for use.

The term “immersion thermostat”, or “probe type thermostat” is a thermostat designed for insertion or at least resembling insertion into the medium being sensed.

A storage water heater includes an immersion thermostat 10, for limiting the temperature of the water therein.

The following description of water immersion thermostat 10 relates to a common product distributed in Israel and other countries.

One of the sensors of immersion thermostat 10 includes a longitudinal metallic sleeve 12. Longitudinal sleeve 12 is inserted into an external metallic sleeve which indeed is immersed in the water. The external sides of the external sleeve touch the water and the internal sides of the external sleeve are dry, and transfer the heat thereof to longitudinal sleeve 12.

The term “substantially-immersed” refers herein to the immersion of an element, such as longitudinal sleeve 12 in water as above described, providing heat transfer between the water and the element, even though the external sleeve avoids wetting of the element.

Thus, longitudinal sleeve 12 is substantially immersed in the water, and will be regarded following as being immersed in the water.

Upon sensing that the water is not too hot, thermostat 10 connects both the phase and the neutral plugs of the power supply to the heating element. Namely, thermostat 10 then connects screw 14 to electric wire 20, and screw 16 to electric wire 18. Upon sensing that the water is extremely hot one or more electric switches disconnects either screw 14 from electric wire 20, or screw 16 from electric wire 18, to turn off the heating element of the storage water heater.

The threshold heat of one of the switches may be adjusted by rotating a flat handle 24. A button 26 may close one of the other switches which was disconnected by extreme heat.

FIGS. 2 and 3 depict the prior art thermostat of FIG. 1 disassembled.

Cover 22 and flat handle 24 are shown removed.

The common prior art thermostat 10 includes two mechanisms, which control three switches. Both of the mechanisms convert heat of the water to a mechanical state.

The first mechanism receives the signal from an internal metal rod 52 (not shown) inside an external longitudinal metal 12. The length of rod 52 is a function of the heat of the water, controlling switch 38.

A bimetallic strip includes two strips of different metals, such as steel and copper joined together, which expand at different rates as they are heated.

The term “stable bimetallic strip” refers herein to a bimetallic strip which retains its state upon expansion above a predetermined threshold.

The second mechanism receives the signal from a stable bimetallic strip (denoted 60 in FIG. 3). Bimetallic strip 60 bends as a function of the heat of the water. Bending above a predetermined threshold disconnects two switches 36.

A “reset type bimetallic strip” refers herein to a stable bimetallic strip which may be reset to the opposing state.

Bimetallic strip 60 may be a reset type bimetallic strip. It may include a springy element which disconnects switches 36 and retains the disconnected state. Manual pressing the springy element after cooling of the water may turn the direction of the springy element to connect switches 36 back.

Metal rod 52 controlling switch 38 is adjusted to a certain temperature between 30 and 75 degrees C. It turns the element heater on and off if the current temperature is below or above the adjusted temperature. Bimetallic strip 60 is a safety component, which cuts the circuit upon a higher temperature, say 110 degrees C., meaning that metal rod 52 has failed.

Thus, the reset activity of bimetallic strip 60 is regarded unsafe after the failure of metal rod 52.

Bimetallic strip 60 is disadvantaged of not being immersed or substantially immersed in the water, thus not sensing the temperature of the deep volume of the water storage.

All the methods described above have not yet provided satisfactory solutions to the long felt need of a safety thermostat.

It is an object of the present invention to provide a reliable and safe immersed thermostat.

It is an object of the present invention to provide a solution to the above-mentioned and other problems of the prior art.

Other objects and advantages of the invention will become apparent as the description proceeds.

SUMMARY OF THE INVENTION

In one aspect the present invention is directed to an improvement in a water immersion thermostat comprising a longitudinal sleeve for being deeply substantially-immersed in water of a storage water heater, the improvement comprising:

-   -   a thermal fuse disposed within the longitudinal sleeve, for         single-use cutting of electrical connection upon temperature of         the water within the storage water heater exceeding a         pre-adjusted temperature threshold; and     -   serial wiring of the thermal fuse between the power supply and         the heating element of the storage water heater,     -   thereby permanently cutting the power supply from the heating         element upon presence of extreme temperature deep in the storage         water heater.

The thermostat may further comprise:

-   -   a multi-use heat sensor disposed within the longitudinal sleeve;         and     -   serial wiring of the thermal fuse between the power supply and         the heating element of the storage water heater,     -   thereby temporally cutting the power supply from the heating         element upon presence of extreme temperature deep in the storage         water heater.

The thermostat may further comprise:

-   -   a triggering element, for flowing electric current through the         serial wiring upon triggering of the thermal fuse.

In another aspect the present invention is directed to a method of using a water immersion thermostat, the method comprising the steps of:

-   -   sensing the temperature deep in the water of the storage water         heater; and     -   permanently cutting the power supply from the heating element of         the storage water heater upon presence of extreme temperature.

The foregoing embodiments of the invention are described and illustrated in conjunction with systems and methods thereof, which are meant to be merely illustrative, and not limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments and features of the present invention are described herein in conjunction with the following drawings:

FIG. 1 depicts a prior art thermostat for a storage water heater.

FIGS. 2 and 3 depict the prior art thermostat of FIG. 1 disassembled.

FIG. 4 depicts a thermostat for a storage water heater, according to one embodiment of the present invention.

FIG. 5 depicts a thermostat for a storage water heater, according to another embodiment of the present invention.

FIG. 6 depicts a thermostat for a storage water heater, according to another embodiment of the present invention.

It should be understood that the drawings are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be understood from the following detailed description of preferred embodiments, which are meant to be descriptive and not limiting. For the sake of brevity, some well-known features, methods, systems, procedures, components, circuits, and so on, are not described in detail.

FIG. 4 depicts a thermostat for a storage water heater, according to one embodiment of the present invention.

Thermostat 10 of the embodiment of FIG. 4 includes the mechanism of internal metal rod 52 inside external longitudinal sleeve 12, for controlling switch 38. According to this embodiment the mechanism of bimetallic strip 60 is cancelled.

A thermal fuse is a single-use element that cuts electrical connection upon extreme temperature.

A thermal fuse 68 is disposed within longitudinal sleeve 12, which is regarded as being immersed in the water.

According to a preferred embodiment thermal fuse 68 replaces bimetallic strip 60. Unlike the prior art bimetallic strip 60 which does not sense the water deep in the water and does not resemble immersion in the water, thermal fuse 68 indeed senses the temperature of the water deep in the water since it is disposed within longitudinal sleeve 12, which is regarded as being immersed in the water.

The sensing of thermal fuse 68 at the same extent of internal metal rod 52, since thermal fuse 68 like internal metal rod 52, even though not touching the water, receives the direct heat of the water through the external metallic sleeve immersed deeply in the water and through longitudinal metallic sleeve 12.

Thermal fuse 68 is a serial electric element between screw 14 and electric wire 20. According to one embodiment the connection between screw 14 and switch 38 is cut; a wire 66 is connected to screw 14, a wire 70 is connected to the edge of switch 36, and thermal fuse 68 is connected to wires 66 and 70.

Similarly another thermal fuse 78 is a serial electric element between screw 16 and electric wire 18. According to one embodiment the connection between screw 16 and the other switch 36 is cut; a wire 74 is connected to screw 14, a wire 76 is connected to switch 36, and thermal fuse 78 is connected to wires 74 and 76.

Since thermal fuses 68 and 78 are single-use elements, the connection is permanently cut, and user cannot turn the heating element on without inviting a technician.

FIG. 5 depicts a thermostat for a storage water heater, according to another embodiment of the present invention.

According to FIG. 4 the current through heating element 108 crosses through thermal fuses 68 and 78.

According to the embodiment of FIG. 5 thermal fuses 68 and 78 of FIG. 4 only allow signaling for allowing current cross through heating element, even though the current through heating element 108 does not cross through thermal fuses 68 and 78.

A triggering element 102 upon sensing current through wires 66 and 70 and through thermal fuse 68, closes its switch for allowing the phase plug to heating element 108. And another triggering element 102 upon sensing current through wires 74 and 76 and through thermal fuse 78, closes its switch for allowing the neutral plug to heating element 108.

FIG. 6 depicts a thermostat for a storage water heater, according to another embodiment of the present invention.

Thermostat 10 of the embodiment of FIG. 6 neither includes metal rod 52 of FIGS. 1,2 and 3 for controlling switch 38, nor includes the mechanism of bimetallic strip 60 of FIGS. 1,2 and 3.

Thermostat 10 of the embodiment of FIG. 6 includes thermal fuse 68 and thermal fuse 78 of FIG. 4, being the safety component instead of bimetallic strip 60. One of the fuses is for the phase connection and the other is for the neutral connection of heating element 108.

Except for the fuses of FIG. 4 thermostat 10 of FIG. 5 includes also a thermistor 90 or another heat sensor which is a multi-use element, instead of metal rod 52. The cutoff temperature of thermistor 90 is lower than the cutoff temperature of thermal fuses 68 and 78.

Thermistor 90 is disposed within longitudinal sleeve 12. Thus thermistor 90 is immersed in the water at the same extent of internal metal rod 52. Thermistor 90, even though not touching the water, receives the direct heat of the water through the external metallic sleeve immersed deeply in the water and through longitudinal metallic sleeve 12.

Thermistor 90 is a serial electric element on the phase connection, i.e. between screw 14 and electric wire 20. The connection is cut at one point, wires 92 and 94 are connected to two sides, namely 96 and 48 of this point, and thermistor 90 is connected to wires 92 and 94.

Thermal fuses 68 and 70, and also thermistor 90 are electric components having pre-adjusted thresholds. These components may be more accurate than the prior art metal rod 52 and bimetallic strip 60, which both are mechanical sensors.

The foregoing description and illustrations of the embodiments of the invention has been presented for the purposes of illustration. It is not intended to be exhaustive or to limit the invention to the above description in any form.

Any term of the claims that has been defined above, has to be interpreted according to this definition. 

What is claimed is:
 1. In a water immersion thermostat comprising a longitudinal sleeve for being deeply substantially-immersed in water of a storage water heater, the improvement comprising: a thermal fuse disposed within said longitudinal sleeve, for single-use cutting of electrical connection upon temperature of the water within said storage water heater exceeding a pre-adjusted temperature threshold; and serial wiring of said thermal fuse between the power supply and the heating element of said storage water heater, thereby permanently cutting said power supply from said heating element upon presence of extreme temperature deep in said storage water heater.
 2. A thermostat according to claim 1, further comprising: a multi-use heat sensor disposed within said longitudinal sleeve; and serial wiring of said thermal fuse between the power supply and the heating element of said storage water heater, thereby temporally cutting said power supply from said heating element upon presence of extreme temperature deep in said storage water heater.
 3. A thermostat according to claim 1, further comprising: a triggering element, for flowing electric current through said serial wiring upon triggering of said thermal fuse.
 4. In a water immersion thermostat comprising a longitudinal sleeve for being deeply substantially-immersed in water of a storage water heater, the method comprising the steps of: sensing the temperature deep in the water of the storage water heater; and permanently cutting the power supply from the heating element of said storage water heater upon presence of extreme temperature. 